Composite structures are commonly manufactured by progressively building up the structure with a plurality of layers of thin composite tape (or tow) laid one layer upon another. Typically, the operation begins by laying one or more tapes onto a starting template or tool that has a configuration generally corresponding to the desired shape of the article to be produced. A tape placement head of a manufacturing system moves over the surface of the template, guiding the one or more tapes of composite material onto the template. The head usually makes repeated passes over the template in a defined pattern until the composite material is entirely collated, building up successive layers of the composite tape to form the desired workpiece. A compaction roller (or other suitable presser device) is typically used for pressing the tape against the workpiece, thereby facilitating adhesion of the successive layers. The workpiece may then be subjected to a curing process (e.g. heating) to further adhere and bond the composite layers. Conventional systems for forming composite structures using successive layers of tape include those systems disclosed, for example, in U.S. Pat. No. 6,799,619 B2 issued to Holmes et al., and U.S. Pat. No. 6,871,684 B2 issued to Engelbart et al.
Composite tape rolls provided for forming composite structures may contain defective material or tape splices where defective material has been removed by the tape manufacturer. These splices can result in random and unpredictable process interruptions during lay up by a composite tape laying machine, causing down time during which the spliced section of the tape must be removed from the composite structure being manufactured. Additionally, reaching the end the tape roll unexpectedly can cause similar problems. To avoid tape flaws, splices, and roll ends, flaw avoidance systems typically use data provided by tape manufacturers that indicates the location of splices or flaws and roll ends to scrap lengths of tape that contain the splices or flaws, or to stop the process in the case of reaching a roll end. In these systems all such location data are referenced to the tape end at the leader of the tape roll.
Although desirable results have been achieved using such prior art systems, there may be room for improvement. For example, tape length can be lost and become unaccounted for by the flaw avoidance system. This results in a loss of the measuring reference to the starting end of the tape and the inability to avoid tape splices, flaws and/or roll ends until manual adjustments are made. However, these manual adjustments may be inaccurate and can contribute to further inability to avoid tape splices. Novel systems and methods that improve the tracking of tape splices by the flaw avoidance systems would therefore have utility.